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Full text of "Text Book Of Mechanical Engineering"

Appendix VI.

1039

l, can be varied to right or left to suit various sizes of work,
to alter the depth of cut. The wheel head is further balanced
by the weight N connected to G by a chain over pullies p p, and
the pulley bracket Q can be adjusted horizontally for changed
position of the saddle. The emery wheel drive from the counter-
shaft is by pulleys r and Y, thence over guide drum q to cones z
arid a, which rotate the drum , and therefore also the wheel
spindle : the lever j serving to tighten the belt z a, and by
tinslacking permit a change of speed to the second step of the
cone. The spur wheels at R are driven from the main cones, and
in turn rotate the cones s and T. This motion is conveyed by
the bevel gear f9 g, and b to the vertical shaft u u, thence through
worm gear at v, and spur pinion oh the shaft w, to a rack upon the
sliding head G, thus causing the vertical traverse. At each rise or
fall of G one of the tappets Y Y strikes the lever/, which puts in
clutch one or other of the bevel wheels at <, thus reversing the
traverse, and the quick and certain throw-over is ensured by the
action of the spring lever d. The worm gear at k, being turned
by hand through a micrometer wheel m, rotates the saddle screw /,
a.nd thus advances the cut: and the lever d puts the bevel wheels
3E out of gear, and thus stops the table rotation when required.
The lever n similarly disconnects the bevels b to permit of hand
traverse by the wheel h.

A combined Internal and Surface Grinding Machine has been
further given in Fig. 938 because of its interest.    The machine is
not large, but is extremely .useful for a number of tool-room
jobs.    On the bed A are three heads, B carrying the work in a
chuck w, while H is the surfacing and D the internal grinding
slide.   The wheel G is driven by pulley F from the first counter-
shaft D, which also drives the mandrel wheel M ; but the small
wheel Q and extra countershaft p are provided for the high speed
required, the train being B to P, Q to R.    The slide H traverses
across, and slide D with the mandrel, both motions occurring,
backward and forward, simultaneously if required ; but the sur-
facing slide only can be stopped (by lever j) while the machine is
in. action.   The traverse motion is obtained through pullies D
and K to three bevel wheels within the bed, as in the previously
described machines, and the reverse is effected by tappets on D